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jvx:server:storage:dbdefault_values [2018/02/02 12:54] admin |
jvx:server:storage:dbdefault_values [2020/06/29 13:31] (current) cduncan Edited for English grammar (capitalization, punctuation, correct verb conjugation) |
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| ~~Title: Considering Database Default Values~~ | ~~Title: Considering Database Default Values~~ | ||
| - | Behind a well-designed database application there is always a well-designed data model. This model ideally fulfills the 3rd NF, or at least a reasonable medium between 2nd and 3rd NF. In the standard case, the user interface visualizes the data modell and allows the collection of master and transaction data. | + | Behind a well-designed database application, there is always a well-designed data model. This model ideally fulfills the third NF, or at least a reasonable medium between second and third NF. In the standard case, the user interface visualizes the data model and allows the collection of master- and transaction data. |
| However, the database offers many advantages that we can apply to the user interface without wasting much time. One of these advantages is the "default value" of columns in tables. | However, the database offers many advantages that we can apply to the user interface without wasting much time. One of these advantages is the "default value" of columns in tables. | ||
| - | Frequently so called flag columns exist, which has a default value configured in the database. An example here are Y/N (= Yes/No) columns. The default value can be N (= No). | + | Frequently, so-called flag columns exist, which have a default value configured in the database. Examples here are the Y/N (Yes/No) columns. The default value can be N (No). |
| - | During the creation of a dataset, the developer would have to consider these default values in the user interface and pre-set them for the user. This is a repetitive and error-prone activity. Besides, the developer would rather spend time on challenging problems that on boring tasks. | + | During the creation of a dataset, the developer would have to consider these default values in the user interface and preset them for the user. This is a repetitive and error-prone activity. Besides, the developer would surely rather spend time on challenging problems than on boring tasks! |
| - | This is where JVx comes in handy. The framework recognizes the default values of columns automatically and assumes the defined values during the creation of new datasets, directly in the user interface. It should be noted, however, that only constant default values are considered, since function calls are always database-dependent and could contain logic. | + | This is where JVx comes in handy. The framework recognizes the default values of columns automatically and assumes the defined values during the creation of new datasets directly in the user interface. It should be noted, however, that only constant default values are considered since function calls are always database-dependent and could contain logic. |
| == Example == | == Example == | ||
| - | Our Application contains user administration for the creation and administration of application users. The underlying database table was created as follows (Oracle Syntax): | + | Our application contains user administration for the creation and administration of application users. The underlying database table was created as follows (Oracle Syntax): |
| <file sql create.sql> | <file sql create.sql> | ||
| Line 45: | Line 45: | ||
| </file> | </file> | ||
| - | We now need a server objekt for access to the database or table: | + | We now need a server object for access to the database or table: |
| <file java> | <file java> | ||